Editing Accurizing (section)

{{Refimprove|date=June 2008}}
{{short description|Process of improving the accuracy and precision of a gun}}
[[File:Unmodified and modified Ruger 10 22 rifles.jpg|thumb|right|250px|[[Ruger 10/22]] [[carbine]]s, before accurizing (top) and after (below). Externally visible changes are the target-style [[stock (firearms)|stock]], the more vertical thumbhole grip, the [[free-floating barrel|free-floated]] [[gun barrel|bull barrel]], and a [[muzzle brake]].]]
'''Accurizing''' is the process of improving the [[accuracy and precision]] of a [[gun]] ([[firearm]] or [[airgun]]).<ref name=glossary>{{cite web|url=http://saami.org/Glossary/index.cfm |title=SAAMI glossary |accessdate=2007-08-30 |url-status=dead |archiveurl=https://web.archive.org/web/20070828104328/http://www.saami.org/Glossary/index.cfm?CFID=6127413&CFTOKEN=94218953&jsessionid=bc302984421186575542868 |archivedate=2007-08-28 }}</ref>

For [[shooting sport]], '''accuracy''' is the gun's ability to hit exactly what the shooter is aiming at, and '''precision''' is the ability to hit the same place over and over again in a repeatable fashion. Both are the goals of accurizing,<ref>"[http://www.chuckhawks.com/accuracy_gun_cartridge_shooter.htm Accuracy: Gun, Cartridge, and Shooter]" by Bob Beers at Chuck Hawks web site</ref> which generally concentrates on four different areas:
*'''Usability''': Enhancements that give the shooter a firmer and more controlled hold on the firearm, as well as a more consistent [[trigger (firearms)|trigger]] pull. Better design [[ergonomics]] is often employed, such as adjustable [[buttstock]]s and grips with more vertical angles that are natural to the human hand and wrist (e.g. [[pistol grip]]). [[Spirit level]]s are often mounted to prevent [[cant (shooting)|cant]]ing, which can vary the points of impact. [[Weapon mount]]s such as [[bipod]]s, [[monopod#Firearms|monopod]]s, [[benchrest]]s, [[shooting sticks (weapon mount)|shooting sticks]] or simply [[sandbag]]s can provide a more stable and relaxed platform for the shooter, and devices such as [[muzzle brake]]s or [[recoil compensator|compensator]]s can also be used to help counter the [[muzzle rise]] from [[recoil]] and re-establish aim faster and more precisely for repeated firing. The use of suitable [[sling (firearms)|sling]]s can also help shooters to stabilize their aim when shooting off-hand while standing or squatting.
*'''Tolerances''': Parts that better fit together will shift less, or shift more consistently, under recoil. [[Rifle bedding]] is one of the most common practices of such accurizing procedure. Adequate screw [[torque]] setting between the [[action (firearms)|action]] and the [[stock (firearms)|stock]] is also important for the overall rigidity of the system. Some companies, such as [[Savage Arms]], have even introduced features like floating [[bolt (firearm)|bolt head]] to provide better bolt-breech engagement for more adequate breech [[seal (mechanical)|seal]] and [[headspace (firearms)|headspacing]].
*'''Harmonics''': The act of firing a gun generates a rapid pressure increase within the [[gun barrel#Bore|barrel bore]], causing the barrel to [[mechanical resonance|resonate]] and [[vibration|vibrate]] in a rope-like fashion. The resultant [[harmonic oscillation]]s of the barrel affect the terminal phase of the projectile's [[internal ballistics]] and in turn the initial status of its [[external ballistics]], and therefore need to be minimized or tuned to limit their effects on accuracy. Generally, the harmonic effects are proportional to the square of the barrel length, and so are generally only of concern in [[long gun]]s such as [[rifle]]s but not [[handgun]]s. Some external accessories, called ''tuners'' or ''de-resonators'', can also be mounted onto the barrel to alter the harmonic wave pattern so that the [[node (physics)|node]] is shifted as near to the [[muzzle (firearms)|muzzle]] as possible. Airguns have significantly lower barrel pressure and are far less affected by barrel harmonics than firearms.
*'''Projectile propulsion consistency''': In airguns, the inbuilt powerplants themselves provide the propulsive force to the [[projectile]], so tuning the gun alone is usually sufficient for accurizing as long as the projectiles' weights and shapes are uniform. Firearms, however, rely purely on [[oxidation|oxidative]] [[chemical reaction]] of the [[gunpowder|powder]] within a [[cartridge (firearms)|cartridge]] to provide propulsive force, and any slight variations in powder load and [[combustion efficiency]] will affect the [[internal ballistics]] of the gun, even if the projectile weights and shape are the same. This means that in addition to the gun itself, consistent ammunition performance is also extremely critical for accuracy with firearms. While some manufacturers produce [[match-grade]] ammunition with smaller [[engineering tolerance|tolerance]]s, it is common for shooters of high-precision disciplines to [[handload]] and fine-tune their own ammunition. Furthermore, the rapid gas expansion that occurs when the projectile leaves the muzzle also [[transitional ballistics|barometrically affects flight behaviour]], so muzzle devices such as [[flash hider]] and [[suppressor]] can also be used to modulate the escaping gas and improve the consistency of shots.

The key to an accurate firearm is consistency. Getting everything to happen the same way for every shot is key to producing small [[shot grouping|grouping]]s, and there are a large number of issues to be addressed in achieving an accurate firearm.<ref name=tacops>{{cite web |url=http://www.tacticaloperations.com/swatapril2000/index.html |title=Tack Driving Tactical Rifle from Tac Ops|accessdate=2007-08-30| archiveurl= https://web.archive.org/web/20071002135156/http://www.tacticaloperations.com/swatapril2000/index.html| archivedate= 2 October 2007 | url-status= live}}</ref><ref name=bullseye>{{cite web |url=http://www.bullseyepistol.com/cstomgun.htm |title=The Custom-Built Handgun|accessdate=2007-08-30| archiveurl= https://web.archive.org/web/20070903091000/http://www.bullseyepistol.com/cstomgun.htm| archivedate= 3 September 2007 | url-status= live}}</ref><ref name=mini14>{{cite web |url=http://outlands.tripod.com/armory/mini-14.htm |title=Accurizing the Mini-14|accessdate=2007-08-30}}</ref><ref name=beretta>{{cite web|url=http://www.gun-tests.com/performance/oct97shootbetter.html|title=Gun-Tests.com Accurizing the Beretta 92FS|accessdate=2007-08-30|archiveurl=https://web.archive.org/web/20070817162628/http://www.gun-tests.com/performance/oct97shootbetter.html|archivedate=17 August 2007|url-status=dead}}</ref> The keys to firing an accurate shot are a firm but not overtight grip, the ability to get a good sight picture and a controlled squeeze of the trigger. The ability to manage recoil is also important in heavily recoiling calibers, both to aid in possible additional shots, and to prevent the user from developing a fear of the recoil.<ref name=grips>{{cite web |url=http://www.bullseyepistol.com/goodgrip.htm |title=The Benefits of Custom Grips by John Dreyer, Encyclopedia of Bullseye Pistol|accessdate=2007-08-30| archiveurl= https://web.archive.org/web/20070927190822/http://www.bullseyepistol.com/goodgrip.htm| archivedate= 27 September 2007 | url-status= live}}</ref>
[[File:Target 223 Savage 10FP 5 shot closeup.jpg|thumb|right|200px|Sample 5-shot [[Shot grouping|group]] measuring 
about {{convert|7|mm|in|abbr=on}} at {{convert|100|yd|order=flip|abbr=on}}, which corresponds to an angular size of about 0.08&nbsp;[[milliradian|mrad]] (0.26&nbsp;[[minute of arc|moa]]).]]
[[File:Target 223 Savage 10FP 25 shot.jpg|thumb|right|200px|Same rifle and load, 25 shots at {{convert|100|yd|order=flip|abbr=on}}. Note that the [[Shot grouping|group size]] is about double, measuring about {{convert|15|mm|in|abbr=on}} at {{convert|100|yd|order=flip|abbr=on}}, which corresponds to an angular size of about 0.15&nbsp;[[milliradian|mrad]] (0.51&nbsp;[[minute of arc|moa]]).]]